[coreboot-gerrit] [S] Change in coreboot[master]: mb/google/rex: Add WWAN poweron sequencing

[Ivy Jian (Code Review)]

Ivy Jian has uploaded this change for review. ( https://review.coreboot.org/c/coreboot/+/67332 )

Change subject: mb/google/rex: Add WWAN poweron sequencing
......................................................................

mb/google/rex: Add WWAN poweron sequencing

The PCIe WWAN module used on rex requires control over 4 signals to
successfully power it on. It is desirable to do this before passing
control to the payload, because the modem requires a ~10 seconds
initialization phase before it can be used.

The corrected sequence looks like:
1) Drive device into full reset and enable power in bootblock
2) Deassert FCPO in romstage, after power rails stabilize
3) Deassert WWAN_RST#, then WWAN_PERST# in ramstage

BUG=b:244077118
TEST=FM350 could be enumerated via lspci

Signed-off-by: Ivy Jian 
Change-Id: I6cda9348ef7f54efe5ba2358040596a1c2da1b13
---
M src/mainboard/google/rex/variants/rex0/gpio.c
1 file changed, 34 insertions(+), 2 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/32/67332/1

diff --git a/src/mainboard/google/rex/variants/rex0/gpio.c b/src/mainboard/google/rex/variants/rex0/gpio.c
index 23a0f5b..52186bc 100644
--- a/src/mainboard/google/rex/variants/rex0/gpio.c
+++ b/src/mainboard/google/rex/variants/rex0/gpio.c
@@ -105,7 +105,7 @@
    /* GPP_C04 : [] ==> EN_WCAM_PWR */
    PAD_CFG_GPO_LOCK(GPP_C04, 0, LOCK_CONFIG),
    /* GPP_C05 : [] ==> WWAN_PERST_L_STRAP */
-	PAD_CFG_GPO(GPP_C05, 0, PLTRST),
+	PAD_CFG_GPO(GPP_C05, 1, PLTRST),
    /* GPP_C06 : [] ==> USI_REPORT_EN */
    PAD_CFG_GPO(GPP_C06, 0, DEEP),
    /* GPP_C07 : [] ==> USI_INT */
@@ -370,14 +370,21 @@

/* Early pad configuration in bootblock */
 static const struct pad_config early_gpio_table_id0[] = {
+	/* GPP_B17 : [] ==> EN_WWAN_PWR */
+	PAD_CFG_GPO(GPP_B17, 1, DEEP),
    /* GPP_B18 : [] ==> SOC_I2C_TPM_SDA */
    PAD_CFG_NF(GPP_B18, NONE, DEEP, NF2),
    /* GPP_B19 : [] ==> SOC_I2C_TPM_SCL */
    PAD_CFG_NF(GPP_B19, NONE, DEEP, NF2),
-
+	/* GPP_C05 : [] ==> WWAN_PERST_L_STRAP (updated in ramstage) */
+	PAD_CFG_GPO(GPP_C05, 0, DEEP),
+	/* GPP_A15 : [] ==> WWAN_RST_L (updated in ramstage) */
+	PAD_CFG_GPO(GPP_A15, 0, DEEP),
    /* GPP_E03 : [] ==> GSC_SOC_INT_ODL */
    PAD_CFG_GPI_APIC(GPP_E03, NONE, PLTRST, LEVEL, INVERT),

+	/* GPP_E07 : [] ==> WWAN_FCPO_L (updated in romstage) */
+	PAD_CFG_GPO(GPP_E07, 0, DEEP),
    /* GPP_H08 : [] ==> UART_DBG_TX_SOC_RX_R */
    PAD_CFG_NF(GPP_H08, NONE, DEEP, NF1),
    /* GPP_H09 : [] ==> UART_SOC_TX_DBG_RX_R */
@@ -414,6 +421,8 @@
 static const struct pad_config romstage_gpio_table_id0[] = {
    /* A20  : [] ==> SSD_PERST_L */
    PAD_CFG_GPO(GPP_A20, 0, DEEP),
+	/* GPP_E07 : [] ==> WWAN_FCPO_L */
+	PAD_CFG_GPO(GPP_E07, 1, DEEP),
 };

const struct pad_config *variant_gpio_table(size_t *num)